A fluorescent probe based on cucurbit[7]uril for the selective recognition of phenylalanine

Abstract

Herein we describe a simple fluorescence quenching method for the selective recognition and determination of the amino acid phenylalanine (Phe). The use of 1 H NMR spectroscopy revealed that the alkaloid palmatine (PAL) can encapsulated partially into the cavity of cucurbit [7]uril (Q[7]) in aqueous solution to form a stable 1:1 host−guest inclusion complex. This host-guest complex exhibits fluorescence of moderate intensity. Interestingly, the addition of the Phe results in a dramatic quenching of the fluorescence intensity associated with the inclusion complex. By contrast, the addition of other natural amino acids resulted in no change in the fluorescence. Based on the linear relationship between the fluorescence intensity and the concentration of Phe, the detection of the concentration of Phe in aqueous solution is facile. Thus, a new fluorescence quenching method for the recognition and determination of the Phe has established herein.

A fluorescent probe for detection of Hg2+ ions constructed by tetramethyl cucurbit[6]uril and 1,2-bis(4-pyridyl)ethene

“…The fluorescence titration curve ( Figure 3a ) shows that at the excitation wavelength of 351 nm, G has an emission peak at a wavelength of 350 nm. With the continuous addition of TMeQ[6], the fluorescence intensity of G is continuously enhanced, and the wavelength is redshifted to 391 nm, indicating that TMeQ[6] interacts with the guest molecule G. The TMeQ[6] cavity may limit the rotation of the pyridine ring on the G molecule, and form an effective conjugated system with another pyridine ring outside the cavity, resulting in enhanced fluorescence [ 40 ]. The molar ratio curve ( Figure 3b ) shows that when TMeQ[6] is added up to 1.0 equiv, the fluorescence intensity of the system gradually stabilizes, confirming that a G and TMeQ[6] inclusion complex is formed with a 1:1 stoichiometry.…”

Selective detection of paraquat by a cucurbit[7]uril-based fluorescent probe

“…45) Also, Yang et al reported a fluorescent probe constructed using Q [7] and PAL for the detection of L-cystine. 46) In the field of cucurbit[n] urils, many fluorescent probes have appeared in the literature constructed from PAL/Q[n] for the detection of a variety of small molecules, [47][48][49][50][51] however few seem to be available for the detection of pesticides. Based on this, we decided to explore if the PAL probe could be encapsulated within the cavity of Q [7] and thereby form an inclusion complex and also if Q [7]-PAL can subsequently be employed for pesticide detection.…”

A study of the inclusion complex formed between cucurcubit[7]uril and 1-[4-(dimethylamino)phenyl]-ethanone

“…a pesticide) can allow for control of properties such as toxicity [24] . In recent years, cucurbit[n]uril assemblies have been involved in many research fields, such as chemistry, materials, environment and biology, and have attracted wide attention [25][26][27][28][29] . Supramolecular assembly systems with novel structures, good rigidity and different properties have been constructed by selecting different construction modes through intermolecular hydrogen bonding, induced dipole, π--π and other weak interactions.…”